I had the same problem but have solved it. My factory setting Umi hammer 4.4.4 kit kat did not have a gps.conf file in the /system/etc you need root access to see it or not in my case. Used FasterGPS from the play store to recreate the gps.conf by running app and choosing the rielevant gepgraphic region.
I have not problem with FIX speed. The problem is instability of the GPS. I jump off the street into the street. GPS is extremely non accurate.
I tried what you wrote, but there is no change :-(
And UMI is silent and does nothing ...
Just for information, the tips I found on needrom (aluminium paper) has solved the problem for 2 french users who's use GPS in their cars with the application Waze. Before the tips they have some issue like loss of signal on the road, bad position on a map etc... and now the GPS works fine.